Raw edible nuts generally have a "beany" flavor which is not pleasant to the taste. It is well known that the flavor of nuts or beans can be improved by roasting. The The roasting is accomplished using either heated air or hot oil. The usual roasting temperatures are about 138.degree. C. to 200.degree. C., depending on the particular nut or bean being roasted and the preferences of the processor.
It is common practice to attempt to modify or improve the flavor of the roasted nut or bean. This is accomplished by the use of coatings and flavor oils.
For example, U.S. Pat. No. 4,161,545, discloses a method for applying a honey based coating to nuts. Similarly, U.S. Pat. No. 3,671,766 discloses a process for coating nuts with hexatol containing compositions. U.S. Pat. No. 4,053,650 discloses a method for coating nuts with cereal and wheat flour compositions which are baked onto the roasted nut. U.S. Pat. No. 4,085,230 discloses a process for processing nuts which includes an initial step of cooking the nuts in boiling water for a period of time before roasting. In a final coating step salt and flavoring are applied to the cooled nuts.
Various nut processing techniques are directed to improved defatted nut products. U.S. Pat. No. 3,294,549 describes a process for reconstituting defatted, pressed peanuts with salts, spices and sweeteners. U.S. Pat. No. 3,740,236 discloses a method for reconstituting defatted nuts and applying a coating containing flavorings. U.S. Pat. No. 4,049,833 discloses a method for processing partially defatted nuts which includes contacting the nuts with a glycerol-containing solution. The process is carried out by heating the nuts to about 200.degree. F. in a water solution of glycerol. A variety of coatings comprising gums, spices, sugar, flavorings and so forth are applied to the surface.
U.S. Pat. No. 3,457,087 discloses a method for eliminating "spotting" on nuts which is associated with blanching and roasting processes. The process involves the quenching of hot roasted nuts in copious amounts of cold oil which is said to be absorbed into the nut. Flavorings can be included in the quench oil.
While the process of U.S. Pat. No. 3,457,087 described above may be effective in preventing nut "spotting" problems, no appreciable flavoring is absorbed by the nut. In fact, none of the prior art processes are successful in having the flavoring absorbed into the structure of the nut. The reason for this is readily apparent from an examination of the roasting process as it affects the nut.
During the initial part of a nut roasting process water is removed from the nut which generally has an initial moisture content of about 4% to 8% by weight. Until the water content is reduced to about 1.5% to 2.5% no browning or flavor development occurs. In addition to loss of water and other volatiles such as aromatics and air the cell structure expands and nut oil moves out of the nut kernel to its surface.
As a result of the loss of volatiles thermal expansion of the nut occurs, forming many small cracks and fissures in the nut. According to U.S. Pat. No. 3,457,087, at this point the nut should be capable of absorbing flavorings readily. However, flavoring added to the hot nuts are generally volatilized and only a minor amount, if any, remains to be absorbed by the nut. Once the nut has cooled the surface oil is absorbed, the nut contracts and the moisture content is equilibrated with the ambient conditions, that is about 2% by weight moisture.
As a result of these physical phenomena of the nut during roasting and cooling, the prior art processes fail to impart substantial flavor to the nut itself. In the process of U.S. Pat. No. 3,457,087, for example, the cold oil is applied to hot nuts and as a consequence the flavoring is volatilized in the region immediately adjacent to the nut. There has been a failure in the prior art to recognize that nut surface temperature during the application of flavorings to nuts is critical if the flavoring is to be absorbed rather than remain merely as a surface coating.